 (defn random
   "random <list> # returns a random item from <list>
    random # generate a random number"
-  {:yb/cat #{:util}}
+  {:yb/cat #{:util :collection}}
   [{items :opts}]
   (if (not (empty? items))
     (rand-nth (ensure-items-collection items))

; split
(defn split
  "split <pattern> <string> # split string with <pattern>"
  {:yb/cat #{:util}}
  [{[_ split-by-str to-split] :match}]
  (let [split-by (re-pattern split-by-str)]
    (s/split to-split split-by)))

; letters
(defn letters
  "letters <string> # turn <string> into a sequence of individual letters"
  {:yb/cat #{:util :collection}}
  [{args :args}]
  (map str (seq args)))

